Devices of this kind are of known art. In modern aeroplanes two devices of this kind are normally deployed for purposes of adjustment of a adjustable flap. Here the adjustment units of the two devices are spaced apart from one another in the wingspan direction, and their actuators are coupled with a central drive via a central torsion shaft train. The torsion shaft train transfers the mechanical drive power of the drive onto the actuators, which in turn actuate the adjustable flap via the kinematic adjustment mechanism.
In flight aerodynamic forces act on the adjustable flaps of a wing; in particular, these are dependent on the setting of the respective adjustable flap relative to the main wing surface, and on the flight speed. As a result of the aerodynamic forces acting on a adjustable flap a so-called flap moment is brought about, which acts on the adjustment units; the latter must apply a corresponding flap counter-moment so as to hold the adjustable flap in the desired setting. With the occurrence of a malfunction event, in particular a critical malfunction event that represents a hazard to safe flying operations, such as, for example, in the event of a fracture occurring in the kinematic adjustment mechanism of one of the adjustment units, it may be the case that one of the adjustment units can no longer apply the necessary flap counter-moment, so that the whole flap counter-moment must be applied by the other intact adjustment unit. This leads in particular to a sudden rise of the flap moment acting on the intact adjustment unit, so that the flap moment is not only statically redistributed onto the intact adjustment unit, but for a short period of time, in addition to the static loading, there is also a dynamic loading acting on the intact adjustment unit. The intact adjustment unit must be designed such that it can accommodate both the dynamic and static loadings acting on it. Since in particular the dynamic loading occurring for a short period of time can be relatively high, it is necessary to design the adjustment units to be very robust, which has a negative effect on the weight of the adjustment unit.